Robert Lee Hayes, nicknamed "Bullet Bob", was an American sprinter and professional football player. After winning gold medals at the 1964 Summer Olympics, he played as a split end in the National Football League (NFL) for the Dallas Cowboys. Hayes is the only athlete to win both an Olympic gold medal and a Super Bowl ring. He was a two-sport standout in college in both track and field and football at Florida A&M University. Hayes was enshrined in the Dallas Cowboys Ring of Honor in 2001 and was selected for induction in the Pro Football Hall of Fame in January 2009. Hayes is the second Olympic gold medalist to be inducted to the Pro Football Hall of Fame, after Jim Thorpe. He once held the world record for the 70-yard dash. He also is tied for the world's second-fastest time in the 60-yard dash. He was once considered the "world's fastest human" by virtue of his multiple world records in the 60-yard, 100-yard, 220-yard, and Olympic 100-meter dashes. He was inducted into the United States Olympic Hall of Fame.

Sprinting is running over a short distance at the top-most speed of the body in a limited period of time. It is used in many sports that incorporate running, typically as a way of quickly reaching a target or goal, or avoiding or catching an opponent. Human physiology dictates that a runner's near-top speed cannot be maintained for more than 30–35 seconds due to the depletion of phosphocreatine stores in muscles, and perhaps secondarily to excessive metabolic acidosis as a result of anaerobic glycolysis.